I'm running 8.0.8 on a raid 5 over 13 disks, and select performance on a
query that needs to join two large tables is very bad. top shows pg
using 2 to 4 percent cpu. Doing a query on one big table uses 30 to 45
percent cpu.
This is RHEL 4 running kernel 2.6.9-22.ELsmp, using an LSI fiber channel
adapter. The disk shelf is one of these:
http://iqstor.com/products/iq1000.htm